Pharmaceutical compositions comprising sulbactam and beta-lactamase inhibitor

ABSTRACT

Pharmaceutical compositions and methods for treating or preventing bacterial infections are disclosed. The pharmaceutical compositions typically comprise pharmaceutically effective amount of: (a) sulbactam or a pharmaceutically acceptable salt thereof, and (b) at least one beta-lactamase inhibitor or a pharmaceutically acceptable salt thereof, with the provision that the beta-lactamase inhibitor is not sulbactam.

RELATED PATENT APPLICATIONS

This application claims the benefit of Indian Patent Application No.2125/MUM/2011 filed on Jul. 26, 2011, the disclosure of which isincorporated herein by reference in its entirety as if fully rewrittenherein. All references including patents, patent applications, andliterature cited in the specification are expressly incorporated hereinby reference in their entirety.

FIELD OF THE INVENTION

The invention relates to antibacterial compositions and methods forpreventing or treating bacterial infections.

BACKGROUND OF THE INVENTION

Resistance to beta-lactam antibiotics is wide spread and a key concern.One of the mechanisms bacteria have developed against beta-lactamantibiotics is production of several beta-lactamase enzymes, whichdeactivate the beta-lactam antibiotics. In general, a typicalbeta-lactam antibiotic alone may not be effective in treating infectionscaused by such beta-lactamase producing bacteria. One alternative totreating infections caused by bacteria producing beta-lactamase enzymesis by co-administration of a beta-lactamase inhibitor with a beta-lactamantibiotic. The beta-lactamase inhibitor prevents deactivation of abeta-lactam antibiotic, typically by binding with the beta-lactamaseenzyme. However, even the combination therapy is also provingineffective in treating infections caused by newer ESBL strains.

Drawz et al. (Clinical Microbiology Reviews, 2010, 23(1), pages 160-201)have reviewed developments in the area of beta-lactamase inhibition andinhibitors. Drawz et al. summarize various beta-lactamase inhibitorsdeveloped to overcome bacterial resistance. Gold et al. (The New EnglandJournal of Medicine, 1996, 335(19), pages 1445-1453) have also reviewedthe subject of antimicrobial drug resistance.

The widespread emergence of newer strains that do not respond to eventhe combination therapies, is becoming a major concern. It is estimatedthat, internationally the prevalence of ESBL in Klebsiella and E. coliis in the range of 30-50% depending upon the geographical location. ForESBLs, carbapenem therapy is the most widely used in the clinicalsettings today. Presently, all strains identified as inhibitor resistantESBLs are treated only by carbapenems. However, some of the emergingESBLs (e.g. those containing metallo-betalactamases, KPCs and Class DESBLs) appear to exhibit higher degree of resistance to evencarbapenems. Thus, there is a need to develop new ways to treatinfections that are becoming resistant to known therapies and methods.

SUMMARY OF THE INVENTION

Accordingly, there are provided pharmaceutical compositions and methodsfor treating or preventing bacterial infections.

In one general aspect, there are provided pharmaceutical compositionscomprising pharmaceutically effective amount of: (a) sulbactam or apharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor or a pharmaceutically acceptable salt thereof,with the provision that the beta-lactamase inhibitor is not sulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising pharmaceutically effective amountof: (a) sulbactam or a pharmaceutically acceptable salt thereof, and (b)at least one beta-lactamase inhibitor or a pharmaceutically acceptablesalt thereof, with the provision that the beta-lactamase inhibitor isnot sulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprisingpharmaceutically effective amount of: (a) sulbactam or apharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor or a pharmaceutically acceptable salt thereof,with the provision that the beta-lactamase inhibitor is not sulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) sulbactam or a pharmaceutically acceptable salt thereof, and (b) atleast one beta-lactamase inhibitor or a pharmaceutically acceptable saltthereof, with the provision that the beta-lactamase inhibitor is notsulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, said methodcomprising administering to said subject a pharmaceutically effectiveamount of: (a) sulbactam or a pharmaceutically acceptable salt thereof,and (b) at least one beta-lactamase inhibitor or a pharmaceuticallyacceptable salt thereof, with the provision that the beta-lactamaseinhibitor is not sulbactam.

The details of one or more embodiments of the invention are set forth inthe description below. Other features, objects and advantages of theinvention will be apparent from the following description includingclaims.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to the exemplary embodiments, and specificlanguage will be used herein to describe the same. It shouldnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Alterations and further modifications ofthe inventive features illustrated herein, and additional applicationsof the principles of the invention as illustrated herein, which wouldoccur to one skilled in the relevant art and having possession of thisdisclosure, are to be considered within the scope of the invention. Itmust be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the content clearly dictates otherwise. All references includingpatents, patent applications, and literature cited in the specificationare expressly incorporated herein by reference in their entirety.

The inventors have surprisingly discovered that a pharmaceuticalcomposition comprising a pharmaceutically effective amount of: (a)sulbactam or a pharmaceutically acceptable salt thereof, and (b) atleast one beta-lactamase inhibitor or a pharmaceutically acceptable saltthereof, with the provision that the beta-lactamase inhibitor is notsulbactam, exhibits unexpectedly improved antibacterial efficacy, evenagainst highly resistant ESBL producing bacteria.

The term “infection” as used herein includes presence of bacteria, in oron a subject, which, if its growth were inhibited, would result in abenefit to the subject. As such, the term “infection” in addition toreferring to the presence of bacteria also refers to normal flora, whichare not desirable. The term “infection” includes infection caused bybacteria.

The term “treat”, “treating” or “treatment” as used herein refers toadministering a medicament, including a pharmaceutical composition, orone or more pharmaceutically active ingredients, for prophylactic and/ortherapeutic purposes. The term “prophylactic treatment” refers totreating a subject who is not yet infected, but who is susceptible to,or otherwise at a risk of infection. The term “therapeutic treatment”refers to administering treatment to a subject already suffering frominfection. The term “treat”, “treating” or “treatment” as used hereinalso refers to administering compositions or one or more ofpharmaceutically active ingredients discussed herein, with or withoutadditional pharmaceutically active or inert ingredients, in order to:(i) reduce or eliminate either a bacterial infection or one or moresymptoms of the bacterial infection, or (ii) retard the progression of abacterial infection or of one or more symptoms of the bacterialinfection, or (iii) reduce the severity of a bacterial infection or ofone or more symptoms of the bacterial infection, or (iv) suppress theclinical manifestation of a bacterial infection, or (v) suppress themanifestation of adverse symptoms of the bacterial infection.

The term “pharmaceutically effective amount” or “therapeuticallyeffective amount” or “effective amount” as used herein refers to anamount, which has a therapeutic effect or is the amount required toproduce a therapeutic effect in a subject. For example, atherapeutically or pharmaceutically effective amount of an antibiotic ora pharmaceutical composition is the amount of the antibiotic or thepharmaceutical composition required to produce a desired therapeuticeffect as may be judged by clinical trial results, model animalinfection studies, and/or in vitro studies (e.g. in agar or brothmedia). The pharmaceutically effective amount depends on severalfactors, including but not limited to, the microorganism (e.g. bacteria)involved, characteristics of the subject (for example height, weight,sex, age and medical history), severity of infection and the particulartype of the pharmaceutically active ingredient used. For prophylactictreatments, a therapeutically or prophylactically effective amount isthat amount which would be effective to prevent a microbial (e.g.bacterial) infection.

The term “administration” or “administering” includes delivery of acomposition or one or more pharmaceutically active ingredients to asubject, including for example, by any appropriate methods, which servesto deliver the composition or it's active ingredients or otherpharmaceutically active ingredients to the site of the infection. Themethod of administration may vary depending on various factors, such asfor example, the components of the pharmaceutical composition or thetype/nature of the pharmaceutically active or inert ingredients, thesite of the potential or actual infection, the microorganism involved,severity of the infection, age and physical condition of the subject anda like. Some non-limiting examples of ways to administer a compositionor a pharmaceutically active ingredient to a subject according to thisinvention includes oral, intravenous, topical, intrarespiratory,intraperitoneal, intramuscular, parenteral, sublingual, transdermal,intranasal, aerosol, intraocular, intratracheal, intrarectal, vaginal,gene gun, dermal patch, eye drop, ear drop or mouthwash. In case of apharmaceutical composition that comprises more than one ingredient(active or inert), one of way of administering such composition is byadmixing the ingredients (e.g. in the form of a suitable unit dosageform such as tablet, capsule, solution, powder and a like) and thenadministering the dosage form. Alternatively, the ingredients may alsobe administered separately (simultaneously or one after the other) aslong as these ingredients reach beneficial therapeutic levels such thatthe composition as a whole provides a synergistic and/or desired effect.

The term “growth” as used herein refers to a growth of one or moremicroorganisms and includes reproduction or population expansion of themicroorganism (e.g. bacteria). The term also includes maintenance ofon-going metabolic processes of a microorganism, including processesthat keep the microorganism alive.

The term, “effectiveness” as used herein refers to ability of atreatment or a composition or one or more pharmaceutically activeingredients to produce a desired biological effect in a subject. Forexample, the term “antibiotic effectiveness” of a composition or abeta-lactam antibiotic refers to the ability of the composition or thebeta-lactam antibiotic to prevent or treat the microbial (e.g.bacterial) infection in a subject.

The term “synergistic” or “synergy” as used herein refers to theinteraction of two or more agents so that their combined effect isgreater than their individual effects.

The term “antibiotic” as used herein refers to any substance, compoundor a combination of substances or a combination compounds capable of:(i) inhibiting, reducing or preventing growth of bacteria; (ii)inhibiting or reducing ability of a bacteria to produce infection in asubject; or (iii) inhibiting or reducing ability of bacteria to multiplyor remain infective in the environment. The term “antibiotic” alsorefers to compounds capable of decreasing infectivity or virulence ofbacteria.

The term “beta-lactam antibiotic” as used herein refers to compoundswith antibiotic properties and containing a beta-lactam nucleus in theirmolecular structure.

The term “beta-lactamase” as used herein refers to any enzyme or proteinor any other substance that breaks down a beta-lactam ring. The term“beta-lactamase” includes enzymes that are produced by bacteria and havethe ability to hydrolyze the beta-lactam ring in a beta-lactamantibiotic, either partially or completely.

The term “beta-lactamase inhibitor” as used herein refers to a compoundcapable of inhibiting activity of one or more beta-lactamase enzymes,either partially or completely.

The term “pharmaceutically inert ingredient” or “carrier” or “excipient”refers to a compound or material used to facilitate administration of acompound, for example, to increase the solubility of the compound. Solidcarriers include, e.g., starch, lactose, dicalcium phosphate, sucrose,and kaolin. Liquid carriers include, e.g., sterile water, saline,buffers, non-ionic surfactants, and edible oils such as oil, peanut andsesame oils. In addition, various adjuvants commonly used in the art maybe included. These and other such compounds are described in theliterature, e.g., in the Merck Index, Merck & Company, Rahway, N.J.Considerations for the inclusion of various components in pharmaceuticalcompositions are described, e.g., in Gilman et al. (Eds.) (1990);Goodman and Gilman's: The Pharmacological Basis of Therapeutics, 8thEd., Pergamon Press.

The term “subject” as used herein refers to vertebrate or invertebrate,including a mammal. The term “subject” includes human, animal, a bird, afish, or an amphibian. Typical, non-limiting examples of a “subject”includes humans, cats, dogs, horses, sheep, bovine cows, pigs, lambs,rats, mice and guinea pigs.

The term “pharmaceutically acceptable salt” as used herein refers to oneor more salts of a given compound which possesses the desiredpharmacological activity of the free compound and which are neitherbiologically nor otherwise undesirable. In general, the“pharmaceutically acceptable salts” refer to salts that are suitable foruse in contact with the tissues of human and animals without unduetoxicity, irritation, allergic response and the like, and arecommensurate with a reasonable benefit/risk ratio. Pharmaceuticallyacceptable salts are well known in the art. For example, S. M. Berge, etal. (J. Pharmaceutical Sciences, 66: 1-19 (1977)), incorporated hereinby reference, describes various pharmaceutically acceptable salts indetails.

The term“trans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide”as used herein refers to a compound also known as Sulfuric acid,mono[(1R,2S,5R)-2-(aminocarbonyl)-7-oxo-1,6-diazabicyclo[3.2.1]oct-6-yl]ester). Any reference to“trans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide”is intended to include its pharmaceutically acceptable salts, pro-drugs,metabolites, esters, ethers, hydrates, polymorphs, solvates, complexes,enantiomers, adducts and its any other pharmaceutically acceptablederivative.

A person of skills in the art would appreciate that various compoundsdescribed herein (including, for example, sulbactam and thebeta-lactamase inhibitor) can exist and are often used as theirpharmaceutically acceptable salts, pro-drugs, metabolites, esters,ethers, hydrates, polymorphs, solvates, complexes, enantiomers, adductsand other pharmaceutically acceptable derivatives. A reference tocompounds discussed herein, therefore, is intended to include suchpharmaceutically acceptable salts, pro-drugs, metabolites, esters,ethers, hydrates, polymorphs, solvates, complexes, enantiomers, adductsand their any other pharmaceutically acceptable derivatives. Forexample, the terms “sulbactam”, and “beta-lactamase inhibitor” includestheir pharmaceutically acceptable salts, pro-drugs, metabolites, esters,ethers, hydrates, polymorphs, solvates, complexes, enantiomers, adductsand their any other pharmaceutically acceptable derivatives.

In one general aspect, there are provided pharmaceutical compositionscomprising pharmaceutically effective amount of: (a) sulbactam or apharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor or a pharmaceutically acceptable salt thereof,with the provision that the beta-lactamase inhibitor is not sulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising pharmaceutically effective amountof: (a) sulbactam or a pharmaceutically acceptable salt thereof, and (b)at least one beta-lactamase inhibitor or a pharmaceutically acceptablesalt thereof, with the provision that the beta-lactamase inhibitor isnot sulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprisingpharmaceutically effective amount of: (a) sulbactam or apharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor or a pharmaceutically acceptable salt thereof,with the provision that the beta-lactamase inhibitor is not sulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) sulbactam or a pharmaceutically acceptable salt thereof, and (b) atleast one beta-lactamase inhibitor or a pharmaceutically acceptable saltthereof, with the provision that the beta-lactamase inhibitor is notsulbactam.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, said methodcomprising administering to said subject a pharmaceutically effectiveamount of: (a) sulbactam or a pharmaceutically acceptable salt thereof,and (b) at least one beta-lactamase inhibitor or a pharmaceuticallyacceptable salt thereof, with the provision that the beta-lactamaseinhibitor is not sulbactam.

The compositions and methods according to this invention use sulbactamor pharmaceutically acceptable salts thereof. If desired, a suitablederivative of sulbactam may also be used. Non-limiting examples of suchsuitable derivatives include pro-drugs, metabolites, esters, ethers,hydrates, polymorphs, solvates, complexes, enantiomers, adducts and alike.

The compositions and methods according to this invention also use one ormore beta-lactamase inhibitors or a pharmaceutically acceptable salt. Ifdesired, a suitable derivative of beta-lactamase inhibitor may also beused. Non-limiting examples of suitable derivatives include pro-drugs,metabolites, esters, ethers, hydrates, polymorphs, solvates, complexes,enantiomers, adducts and a like of such beta-lactamase inhibitors. Ingeneral, any compound capable of inhibiting activity of one or morebeta-lactamase enzymes, either partially or completely, can beadvantageously used in the compositions and methods according to thisinvention.

In some embodiments, sulbactam in the composition and/or methodsaccording to the invention is present as sulbactam sodium.

In some embodiments, the beta-lactamase inhibitor in the compositionand/or methods according to the invention is at least one selected fromtazobactam, clavulanic acid andtrans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide,or a pharmaceutically acceptable salt thereof.

In some other embodiments, the beta-lactamase inhibitor in thecomposition and/or methods according to the invention istrans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide,or a pharmaceutically acceptable salt thereof.

In some other embodiments, the beta-lactamase inhibitor in thecomposition and/or methods according to the invention is sodium salt oftrans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide.

The pharmaceutical compositions according to this invention can exist invarious forms. In some embodiments, the pharmaceutical composition is inthe form of a powder or a solution.

In some embodiments, the pharmaceutical compositions according to theinvention are in the form of a powder that can be reconstituted byaddition of a compatible reconstitution diluent prior to parenteraladministration. Non-limiting example of such a compatible reconstitutiondiluent includes water.

In some other embodiments, the pharmaceutical compositions according tothe invention are in the form of a frozen composition that can bediluted with a compatible diluent prior to parenteral administration.

In some other embodiments, the pharmaceutical compositions according tothe invention are in the form ready to use for parenteraladministration.

The amount of sulbactam and beta-lactamase inhibitor in the compositionmay vary depending on the specific requirements. In some embodiments,sulbactam is present in the composition in an amount from about 0.01 toabout 10 gm. In some other embodiments, beta-lactamase inhibitor ispresent in the composition in an amount from about 0.01 to about 10 gm.Amounts below or above these ranges may also be employed, if desired.

In the methods according to the invention, the amount of sulbactam andbeta-lactamase inhibitor that may be administered to a subject may varydepending on the specific requirements. In some embodiments, sulbactamis administered in an amount from about 0.01 to about 10 gm per day. Insome other embodiments, beta-lactamase inhibitor is administered in anamount from about 0.01 to about 10 gm per day. Amounts below or abovethese ranges may also be administered, if desired.

In the methods according to the invention, the pharmaceuticalcomposition and/or other pharmaceutically active ingredients (including,for example, one or more of sulbactam and beta-lactamase inhibitor) maybe administered by any appropriate method, which serves to deliver thecomposition or its constituents or the active ingredients to the desiredsite. The method of administration can vary depending on variousfactors, such as for example, the components of the pharmaceuticalcomposition and nature of the active ingredients, the site of thepotential or actual infection, the microorganism (e.g. bacteria)involved, severity of infection, age and physical condition of thesubject. Some non-limiting examples of administering the composition toa subject according to this invention include oral, intravenous,topical, intrarespiratory, intraperitoneal, intramuscular, parenteral,sublingual, transdermal, intranasal, aerosol, intraocular,intratracheal, intrarectal, vaginal, gene gun, dermal patch, eye drop,ear drop or mouthwash.

The compositions according to the invention can be formulated intovarious dosage forms wherein the active ingredients (e.g. sulbactam andbeta-lactamase inhibitor) may be present either together (e.g. as anadmixture) or as separate components. When the various ingredients inthe composition are formulated as a mixture, such composition can bedelivered by administering such a mixture. The composition or dosageform wherein the ingredients do not come as a mixture, but come asseparate components, such composition/dosage form may be administered inseveral ways. In one possible way, the ingredients may be mixed in thedesired proportions and the mixture is then administered as required.Alternatively, the individual components or ingredients (active orinert) may be separately administered (simultaneously or one after theother) in appropriate proportions so as to achieve the same orequivalent therapeutic level or effect as would have been achieved byadministration of the equivalent mixture.

Similarly, in the methods according to the invention, the activeingredients (including, for example, one or more of sulbactam andbeta-lactamase inhibitor) may be administered to a subject in severalways depending on the requirements. In some embodiments, the activeingredients are admixed in appropriate amounts and then the admixture isadministered to a subject. In some other embodiments, the activeingredients are administered separately. Since the inventioncontemplates that the active ingredients agents may be administeredseparately, the invention further provides for combining separatepharmaceutical compositions in kit form. The kit may comprise one ormore separate pharmaceutical compositions, each comprising one or moreactive ingredients. Each of such separate compositions may be present ina separate container such as a bottle, vial, syringes, boxes, bags, andthe like. Typically, the kit comprises directions for the administrationof the separate components. The kit form is particularly advantageouswhen the separate components are preferably administered in differentdosage forms (e.g., oral and parenteral) ore are administered atdifferent dosage intervals. When the active ingredients are administeredseparately, they may be administered simultaneously or sequentially.

The pharmaceutical composition or the active ingredients according tothe present invention may be formulated into a variety of dosage forms.Typical, non-limiting examples of dosage forms include solid,semi-solid, liquid and aerosol dosage forms; such as tablets, capsules,powders, solutions, suspensions, suppositories, aerosols, granules,emulsions, syrups, elixirs and a like.

In general, the pharmaceutical compositions and method disclosed hereinare useful in preventing or treating bacterial infections.Advantageously, the compositions and methods disclosed herein are alsoeffective in preventing or treating infections caused by bacteria thatare considered be less or not susceptible to one or more of knownbeta-lactam antibiotic or their known compositions. Some non-limitingexamples of such bacteria known to have developed resistance to variousantibacterial agents include Acinetobacter, E. coli, Pseudomonasaeruginosa, Staphylococcus aureus, Enterobacter, Klebsiella, Citrobacterand a like. Other non-limiting examples of infections that may beprevented or treated using the compositions and/or methods of theinvention include: skin and soft tissue infections, febrile neutropenia,urinary tract infection, intraabdominal infections, respiratory tractinfections, pneumonia (nosocomial), bacteremia meningitis, surgical,infections etc.

Surprisingly, the compositions and methods according to the inventionare also effective in preventing or treating bacterial infections thatare caused by bacteria producing one or more beta-lactamase enzymes. Theability of compositions and methods according to the present inventionto treat such resistant bacteria represents a significant improvement inthe art.

It will be readily apparent to one skilled in the art that varyingsubstitutions and modifications may be made to the invention disclosedherein without departing from the scope and spirit of the invention. Forexample, those skilled in the art will recognize that the invention maybe practiced using a variety of different compounds within the describedgeneric descriptions.

EXAMPLES

The following examples illustrate the embodiments of the invention thatare presently best known. However, it is to be understood that thefollowing are only exemplary or illustrative of the application of theprinciples of the present invention. Numerous modifications andalternative compositions, methods, and systems may be devised by thoseskilled in the art without departing from the spirit and scope of thepresent invention. The appended claims are intended to cover suchmodifications and arrangements. Thus, while the present invention hasbeen described above with particularity, the following examples providefurther detail in connection with what are presently deemed to be themost practical and preferred embodiments of the invention.

Example 1

The efficacy of compositions and methods in treating bacterialinfections was studied. In a typical study, overnight grown bacterialcultures were diluted appropriately and inoculated on the agar mediacontaining doubling dilutions of composition or pharmaceutically activeingredients disclosed herein. Observation for growth or no growth wasperformed after 16-20 hours of incubation at 35±2° C. in ambient air.The overall procedure was performed as per Clinical and LaboratoryStandards Institute (CLSI) recommendations (Clinical and LaboratoryStandards Institute (CLSI), performance Standards for AntimicrobialSusceptibility Testing, 20th Informational Supplement, M 100-S20, Volume30, No. 1, 2010). The results of the study are summarized in Table 1.

Table 1 details results of the activity study using Sulbactam andNXL-104 (beta-lactamase inhibitor), alone and in combination with eachother. NXL-104 is sodium salt oftrans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide.As can be seen from the data given in Table 1, each of sulbactam andNXL-104 have much higher MIC values indicating their lower antibioticeffectiveness, when used alone. A combination comprising ESBL inhibitorssulbactam and NXL-104 showed significant enhancement in the antibioticeffectiveness as compared when these were used alone. As can be seen,the overall MIC values for a combination comprising sulbactam andNXL-104 are much lower than those obtained with them when used alone.These finding are even more unexpected since the bacterial strainsemployed in this study are typically classified as ESBL strains withvery high degree of resistance to beta-lactam antibiotics includingcarbapenems and the agents used in the study are generally employedunder clinical conditions as ESBL inhibitors and are not associated withsignificant stand alone antibiotic activity. Thus, a combination ofSulbactam with at least one beta-lactamase inhibitor brings aboutsurprising antibiotic activity, which is even superior to Cefepime aloneand its combination with either Sulbactam or NXL-104.

TABLE 1 Activity of sulbactam and NXL-104 (alone and in combination witheach others) MIC (mcg/ml) of NXL-104 MIC of cefepime (mcg/ml) inpresence of In presence of In presence of ESBL MIC (mcg/ml) SulbactamSulbactam NXL-104 Sr. Strain NXL-104 Sulbactam Cefepime (4 mcg/ml) (4 to8 mcg/ml) (4 to 8 mcg/ml) 1. A. baumanii >64 >32 >32 2 >32 >32 13301 2.A. baumanii >64 >32 >32 2 >32 16 13304 3. A. baumanii >64 16 16 2 4 1613305 4. A. baumanii >64 >32 >32 16 >32 32 S-3 5. A.baumanii >64 >32 >32 16 >32 32 S-4 6. A. baumanii >64 >32 32 16 32 16S-8 7. A. baumanii >64 >32 >32 16 >32 16 S-10 8. A. baumanii >64 >32 >3216 >32 16 S-15

1. A pharmaceutical composition comprising pharmaceutically effectiveamount of: (a) sulbactam or a pharmaceutically acceptable salt thereof,and (b) at least one beta-lactamase inhibitor or a pharmaceuticallyacceptable salt thereof, with the provision that the beta-lactamaseinhibitor is not sulbactam.
 2. A pharmaceutical composition according toclaim 1, wherein the composition is in the form of a powder or asolution.
 3. A pharmaceutical composition according to claim 1, whereinsulbactam or a pharmaceutically acceptable salt thereof is present in anamount from about 0.01 to about 10 gm.
 4. A pharmaceutical compositionaccording to claim 1, wherein the beta-lactamase inhibitor or apharmaceutically acceptable salt thereof is present in an amount fromabout 0.01 to about 10 gm.
 5. A method for preventing or treating abacterial infection in a subject, said method comprising administeringto said subject a pharmaceutically effective amount of a pharmaceuticalcomposition according claim
 1. 6. A method for preventing or treating abacterial infection in a subject, said infection being caused bybacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition according to claim 1.7. A pharmaceutical composition according to claim 1, wherein sulbactamor a pharmaceutically acceptable salt thereof, and the beta-lactamaseinhibitor or a pharmaceutically acceptable salt thereof, are present inadmixture or as separate components.
 8. A pharmaceutical compositionaccording to claim 1, wherein the composition is in the form of a powderthat can be reconstituted by addition of a compatible reconstitutiondiluent prior to parenteral administration.
 9. A pharmaceuticalcomposition according to claim 1, wherein the composition is in the formof a frozen composition that can be diluted with a compatible diluentprior to parenteral administration.
 10. A pharmaceutical compositionaccording to claim 1, wherein the composition is in a form ready to usefor parenteral administration.
 11. A method for preventing or treating abacterial infection in a subject, said method comprising administeringto said subject a pharmaceutically effective amount of: (a) sulbactam ora pharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor or a pharmaceutically acceptable salt thereof,with the provision that the beta-lactamase inhibitor is not sulbactam.12. A method for preventing or treating a bacterial infection in asubject, said infection being caused by bacteria producing one or morebeta-lactamase enzymes, said method comprising administering to saidsubject a pharmaceutically effective amount of: (a) sulbactam or apharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor or a pharmaceutically acceptable salt thereof,with the provision that the beta-lactamase inhibitor is not sulbactam.13. A pharmaceutical composition according to claim 1 or a methodaccording to claims 11 to 12, wherein sulbactam is present as sulbactamsodium.
 14. A pharmaceutical composition according to claim 1 or amethod according to claims 11 to 12, wherein the beta-lactamaseinhibitor is at least one selected from tazobactam, clavulanic acid andtrans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide15. A pharmaceutical composition according to claim 1 or a methodaccording to claims 11 to 12, wherein the beta-lactamase inhibitor is asodium salt oftrans-7-oxo-6-(sulphooxy)-1,6-diazabicyclo-[3.2.1]-octane-2-carboxamide.16. A method according to claims 11 to 12, wherein sulbactam or apharmaceutically acceptable salt thereof, and the beta-lactamaseinhibitor or a pharmaceutically acceptable salt thereof are administeredseparately or as a combined dosage form.